Mold for forming a molding member and method of fabricating a molder member using the same

ABSTRACT

There are provided a mold for forming a molding member and a method for forming a molding member using the same. The mold includes an upper surface, and a lower surface having an outer peripheral surface and a concave surface surrounded by the outer circumference. Injection and discharge holes extend from the upper surface to the lower surface. Accordingly, after the mold and the package are coupled so that the discharge hole is directed upward, a molding member can be formed on the package by injecting the molding material through the injection hole, whereby it is possible to prevent air bubbles from being captured in the molding member.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 11/995,196, filed on Jan. 9, 2008, which is the National Stageof International Application No. PCT/KR2006/002462, filed Jun. 26, 2006,and claims priority of Korean Patent Application No. 10-2005-0063361,filed Jul. 13, 2005, to all of which are hereby incorporated byreference for all purposes as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to a mold and a method for forming amolding member using the same, and more particularly, to a mold forforming a lens-shaped molding member on a package and a method forforming a molding member using the same.

BACKGROUND OF THE INVENTION

Generally, a light emitting device includes a package with an LED (LightEmitting Diode) mounted thereon and a lens for covering the LED forimproving a light emission efficiency within a certain range of viewingangles. This lens may be produced in advance by casting or the like andthen coupled on the package, but the lens and package are weaklyadhered. Accordingly, a molding technique is used to form a lens-shapedmolding member on a package with an epoxy or silicone resin.

A method of forming a molding member using resin is disclosed in U.S.Patent Publication No. 2003/0168720, by Kamada, entitled “SemiconductorDevice and Manufacturing Method for same.” FIG. 1 is a sectional viewillustrating a method of forming a molding member by Kamada.

Referring to FIG. 1, a metal plate is perforated to form a frameincluding metal leads (not shown), an air vent frame 303, and aninjection frame 305, and a pressing process is performed to positionends of the metal leads below the frames 303 and 305, thereby completingthe frame.

Then, a package support 304 (or a package body) is formed by injectionmolding. At this time, a heat sink 302 and the lead frame may beinsertion-molded in a die to form the package body 304. The package body304 has a recess exposing the ends of the metal leads and the heat sink302 and has gates 306 adjacent to the frames 303 and 305.

Thereafter, an LED 301 is mounted on the heat sink 302 and iselectrically connected to the metal leads through wire bonding.

Subsequently, a predetermined surface of an upper mold 401 is pressed tobe adjacent to an upper surface of the package body 304. The upper mold401 is shaped to have a trench for guiding a molding material to beinjected, a trench for guiding gas, and recesses and protrusions forforming the molding member into a desired shape. The molding materialflows to the gate 306 along the upper surface of the injection frame305, and gas is discharged along the upper surface of the air vent frame303 as being filled with the molding material. Accordingly, a space 403is filled with the molding material, thereby forming a molding memberwith a desired shape. Meanwhile, a lower mold 402 having a recessreceiving the package body 304 is pressed so that the entire packagebody 304 and the lead frame are in place.

According to the conventional method, there are advantages in thatseveral molding members can be successively formed using a transfermolding method and resin burrs can be prevented by adopting the frames303 and 305.

However, when the space 403 is filled with the molding material, thegate 306 at a side of the air vent frame 303 may be clogged with themolding material before the space 403 is completely filled with themolding material. Accordingly, the gas in the space 403 may not bedischarged completely, but captured in the molding material. The gascaptured in the molding material may cause inferior curing of themolding member and decrease uniformity and efficiency of the lightemitted through the molding member.

An object of the present invention is to provide a mold capable ofpreventing gas from being captured in a molding material.

Another object of the present invention is to provide a method offorming a molding member, which can prevent gas from being captured inthe molding material.

A further object of the present invention is to provide a method offorming a molding member, which can prevent burr from being generated.

In order to accomplish these objects, the present invention provides animproved mold for forming a molding member on a package, and a method offorming a molding member using the mold. In one aspect of the presentinvention, there is provided a mold including an upper surface; and alower surface having an outer peripheral surface and a concave surfacesurrounded by the outer peripheral surface. Injection and dischargeholes extend from the upper surface to the lower surface. Accordingly,after the mold and the package are coupled so that the discharge hole isdirected upward, a molding material can be injected through theinjection hole to form a molding member on the package, whereby it ispossible to prevent air bubbles from being captured in the moldingmember.

The injection and discharge holes may extend from the upper surface tothe outer peripheral surface of the lower surface. Accordingly, it maybe prevented that the molding material contained in the injection anddischarge holes is remained on the upper surface of the molding memberwith a desired shape.

In another aspect of the present invention, there is provided a methodof forming a molding member. The method comprises preparing a moldincluding an upper surface, and a lower surface having an outerperipheral surface and a concave surface surrounded by the outerperipheral surface. The mold includes injection and discharge holesextending from the upper surface to the lower surface. In addition, apackage having an LED mounted thereon is prepared. The package and themold are coupled to each other. At this time, the package and the moldare coupled so that the concave surface covers the LED, the outerperipheral surface is adjacent to an upper surface of the package, anedge portion of the package adjacent to the discharge hole is directedupward, and an other edge portion opposite to the edge portion of thepackage is directed downward. Then, a molding material is injected intothe injection hole. As the molding material is injected into theinjection hole, a space between the concave surface and the uppersurface of the package is filled with the molding material, and innergas is discharged through the discharge hole. Since the discharge holeis positioned in an upper portion, the gas in the space can bedischarged before the discharge hole is clogged with the moldingmaterial. Accordingly, it is prevented that the gas is captured in themolding material.

Meanwhile, the preparation of the package comprises preparing a leadframe having lead electrodes. The package body is formed on the leadframe. The package body has a recess exposing the lead electrodes. Inaddition, the lead electrodes protrude out of the package body. The LEDis mounted in the recess region, and the LED is electrically connectedwith the lead electrodes.

The package body may have a guide groove for guiding the moldingmaterial injected through the injection hole toward the recess and aguide groove for guiding inner gas to the discharge hole. Accordingly,it is prevented that the molding material contained in the injection anddischarge holes is remained on the upper surface of the molding memberwith a desired shape.

According to the present invention, it is possible to provide animproved mold capable of preventing gas from being captured in a moldingmaterial, and also to provide a method of forming a molding membercapable of preventing gas from being captured in the molding materialusing the mold. In addition, the present invention may provide a methodof forming a molding member capable of preventing resin burrs from beinggenerated on lead electrodes.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a conventional method of forminga molding member;

FIGS. 2 to 5 are sectional views illustrating a method of forming amolding member according to an embodiment of the present invention,wherein FIG. 3 is an exploded sectional view of FIG. 2;

FIG. 6 is a sectional view illustrating a molding member formedaccording to the embodiment of the present invention; and

FIG. 7 is a sectional view of a package, which illustrates a method offorming a molding member according to another embodiment of the presentinvention.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Thefollowing embodiments are provided only for illustrative purposes sothat those skilled in the art can fully understand the spirit of thepresent invention. Therefore, the present invention is not limited tothe following embodiments but may be implemented in other forms. In thedrawings, the widths, lengths, thicknesses and the like of elements areexaggerated for convenience of illustration. Like reference numeralsindicate like elements throughout the specification and drawings.

FIGS. 2 to 5 are sectional views illustrating a method of forming amolding member according to an embodiment of the present invention.Here, FIG. 3 is an exploded sectional view of FIG. 2.

Referring to FIGS. 2 and 3, a mold 20 for forming a molding member on apackage is prepared. The mold 20 has an upper surface 24, and a lowersurface having an outer peripheral surface 25 a and a concave surface 25b surrounded by the outer peripheral surface. The upper surface 24 andthe lower surface may be connected through a side as shown in thefigures, but it is not limited thereto, and the upper surface 24 and thelower surface may be connected with each other without any side. Thus,the upper surface of the mold 20 is not limited to a flat surface, butmay have various shapes.

The concave surface of the mold 20 has a shape corresponding to amolding member with a desired shape. Grooves and/or protrusions may beformed in the concave surface.

Meanwhile, the outer peripheral surface 25 a which is adjacent to anupper surface of the package may be a flat surface, but it is notlimited thereto. The outer peripheral surface 25 a may also be aninclined surface for forming a space between the upper surface of thepackage and the outer peripheral surface 25 a of the mold 20, or groovesmay be formed in the outer peripheral surface 25 a. In addition, aprotrusion 26 for surrounding a sidewall of the package may be formed onan edge of the outer peripheral surface 25 a. The protrusion 26 may becontinuous or discontinuous along the edge of the outer peripheralsurface 25 a.

An injection hole 23 a and a discharge hole 23 b extend from the uppersurface 24 to the lower surface. The injection and discharge holes 23 aand 23 b are through-holes passing through the mold 20. The injectionand discharge holes 23 a and 23 b may respectively extend from the uppersurface 23 to the concave surface 25 b, but preferably extend to theouter peripheral surface 25 a. At this time, the outer peripheralsurface 25 a having the discharge hole 23 a formed therethrough may havea groove (not shown) connected from the discharge hole 23 b to theconcave surface 25 b. The groove forms a sufficient space between theupper surface of the package and the mold, thereby allowing air to beeasily discharged. Meanwhile, the injection and discharge holes 23 a and23 b may be arranged to face each other with the concave surface 25 bbeing interposed therebetween as shown in the figures, but they are notlimited thereto. The injection and discharge holes are spaced apart fromeach other.

The mold 20 may be formed using an injection molding technique. At thistime, a connection frame 21 may be insertion-molded to form a pluralityof molds 20, and accordingly a plurality of the molds 20 may beconnected to each other by the connection frame 21 and used as a singleunit.

The injection hole 23 a is formed to be perpendicular to the connectionframe 21 or preferably to be inclined from a center of the upper surface24 toward the outside of the lower surface. It will be explained below.Meanwhile, like the injection hole 23 a, the discharge hole 23 b mayalso be formed to be perpendicular or inclined.

In the meantime, a package 10 with an LED 15 mounted thereon isprepared. The preparation of the package 10 includes preparing a leadframe 11 having lead electrodes. The lead frame 11 may be formed byperforating a metal plate such as Cu or A1 plate. According to the priorart, ends of the lead electrodes are positioned below the frame using apressing process, but this process can be excluded from the embodimentsof the present invention.

Thereafter, a package body 13 having a recess exposing the leadelectrodes is formed on the lead frame 11. The package body 13 may beformed using an insertion molding technique and made of thermosetting orthermoplastic resin. Guide grooves 13 a and 13 b connected to the recessmay be formed in the upper surface of the package body 13. The guidegroove 13 a is formed at a position corresponding to the injection hole23 a of the mold 20, and the guide groove 13 b is formed at a positioncorresponding to the discharge hole 23 b of the mold 20. Meanwhile, thelead electrodes protrude out of the package body 13. For convenience,the package 13 is classified into an upper part and a lower part withrespect to the lead electrodes.

Meanwhile, the LED 15 is mounted in the recess region. The LED 15 may bemounted on the lead electrode as shown in the figures, but it is notlimited thereto. The LED 15 may also be mounted on the upper surface ofthe package body 13 in the recess. The LED 15 is electrically connectedto the lead electrodes through bonding wires. In a case of a 1-bond diehaving electrodes formed on its upper and lower surfaces respectively,the LED 15 may be adhered on the lead electrode using a conductiveadhesive and the upper electrode of the LED 15 may be connected to theother lead electrode through a bonding wire. In a case of a 2-bond diehaving two electrodes formed on its upper surface, two electrodes of theLED 15 are connected to the lead electrodes through bonding wires.Meanwhile, the LED 15 may be mounted on a sub-mount (not shown), and thesub-mount may be connected to the lead electrodes through bonding wires.

The package 10 is coupled to the mold 20 so that the concave surface 25b of the mold covers the LED 15 and the outer peripheral surface 25 a isadjacent to the upper surface of the package body 13. At this time, theprotrusion 26 of the mold 20 surrounds the upper part of the packagebody 13. The protrusion 26 reduces leakage of the molding materialbetween the mold 20 and the package body 13, and also aligns the mold 20and the package body 10.

Meanwhile, in order to prevent a molding material leaked between themold 20 and the package body 13 from being adhered to the leadelectrodes, the lead frame 11 may be covered with a cover seat 41. Thecover seat 41 has a through-hole 41 a through which the package body 13is allowed to pass.

In the embodiments of the present invention, the mold 20 and the package10 are securely coupled, and various coupling means may be used for thispurpose. For example, as shown in the figures, the mold 20 and thepackage 10 may be coupled using jigs 31 and 33.

More specifically, the lower jig 31 has a recess 31 a for receiving thepackage body 13. The lower part of the package body 13 is received inthe recess 31 a of the lower jig 31, and the lead frame 11 is seated onthe upper surface of the lower jig 31. Meanwhile, the cover seat 41 maycover not only the lead frame 11 but also the upper surface of the lowerjig 31, and may also prevent the molding material from being adhered tothe lower jig 31.

In the meantime, the upper jig 33 is coupled to an upper portion of themold 20 and presses the mold 20 against the lower jig 31. The upper jig33 has a through-hole 33 a for exposing the injection and dischargeholes 23 a and 23 b of the mold 20. The through-hole 33 a may be sizedsuch that the upper surface 24 of the mold 20 may pass therethrough, asshown in the figures, but it is not limited thereto and the through-hole33 a may have various sizes and/or shapes. In a case where a pluralityof the molds 20 are connected with the connection frame 21, the upperjig 33 may press the connection frame 21 so that the mold 20 is pressedtoward the lower jig 31. Then, the lower jig 31 and the upper jig 33 arecoupled using a fastening means such as pins, screws or clamps (notshown). Accordingly, the mold 20 and the package 10 may be securelycoupled to each other.

Referring to FIG. 4, the mold 20 and the package 10 coupled with eachother are rotated such that an edge portion of the package body 13adjacent to the discharge hole 23 b is directed upward and the otherportion opposite to the edge portion of the package body 13 is directeddownward. Accordingly, in the space surrounded by the package body 13and the mold 20, the guide groove 13 b is positioned above. Meanwhile,in a case where the injection hole 23 a is formed at a position oppositeto the discharge hole 23 b, the injection hole 23 a and the guide groove13 a are positioned below.

In this embodiment, the mold 20 and the package 10 are rotated afterbeing coupled, but the mold 20 and the package 10 may also be coupledafter being rotated.

Then, a molding material such as epoxy or silicone resin is injectedthrough the injection hole 23 a. The molding material may containphosphors and/or diffusers. The molding material fills the space fromits bottom, and the gas in the space is discharged to the outsidethrough the guide groove 13 b and the discharge hole 23 b. Since theguide groove 13 b and the discharge hole 23 b are positioned in theupper portion of the space, the gas may be continuously dischargedthrough the discharge hole 23 b until the space is completely filledwith the molding material. Accordingly, it is prevented that the innergas is captured in the molding material.

Meanwhile, in order to prevent the molding material from flowing backthrough the injection hole 23 a, the injection hole 23 a is formed to beperpendicular to the upper surface of the package body 13 or preferablyto be inclined toward the center of the mold 20 from the lower surfaceto the upper surface 24 of the mold 20.

Referring to FIG. 5, after the space is completely filled with themolding material, the molding material is cured and forms a moldingmember 35. The molding material may be cured in a state where the jigs31, 33 are coupled. Also, the curing process may also be conducted afterthe mold 20 rotates to face upward.

Referring to FIG. 6, after the curing process is completed, the jigs 31and 33 and the cover seat 41 are separated and removed. As a result, apackage with the molding member 35 of a desired shape is completed.

The shape of the molding member 35 is determined according to the shapeof the concave surface 25 b of the mold 20. Thus, it is possible to formthe molding member 35 of a variety of shapes by changing the shape ofthe concave surface 25 b of the mold 20. The molding material, which isconnected to the molding member 35 and cured in the guide grooves 13 aand 13 b, may remain therein.

In this embodiment, it has been exemplarily explained that the moldingmember 35 is formed on the package 10 with a recess, but the presentinvention is not limited thereto. The present invention may also beapplied to a case where a molding member to cover an LED is formed on apackage without a recess. Meanwhile, the present invention may also beapplied to a package employing a heat sink, and FIG. 7 is a sectionalview illustrating a method of forming such a package 50.

Referring to FIG. 7, a lead frame 51 is formed by a perforating processas described with reference to FIGS. 2 and 3. At this time, ends of leadelectrodes are spaced apart from each other. Then, a package body 53with a recess exposing the lead electrodes is formed. The package body53 also has a through-hole connected to the recess and passing throughthe lower surface of the package body 53. Meanwhile, the package body 53may have guide grooves 53 a and 53 b in its upper surface, like thepackage body 13 of FIG. 2. The guide grooves 53 a and 53 b may bemodified in various ways and expose the lead electrodes as shown in thefigure.

Meanwhile, a heat sink 57 is inserted into the through-hole. The heatsink 57 may have a wide lower surface in order to promote heatdissipation and also have a protrusion on its center region. Theprotrusion is inserted into the through-hole and protrudes into therecess region.

An LED 55 is mounted on the upper surface of the heat sink 57 andelectrically connected to the lead electrodes through bonding wires. Thelead electrodes and the LED may be connected through the bonding wire invarious ways. In a case where the heat sink 57 is conductive, the heatsink and the lead electrode may be connected using a bonding wire.

In this embodiment, the heat sink 57 is inserted after the package body53 is formed, but it is not limited thereto. The heat sink and the leadframe may also be insertion-molded together to form a package body as inthe prior art. After the heat sink 57 is coupled to the lead frame 51 inadvance, the heat sink and the lead frame may also be insertion-moldedto form a package body.

Then, the processes as explained with reference to FIGS. 2 to 6 areperformed to form a molding member to the package 50.

1. A mold for forming a molding member on a package, comprising: anupper surface; a lower surface having an outer peripheral surface and aconcave surface surrounded by the outer peripheral surface; andinjection and discharge holes extending from the upper surface to thelower surface; and a protrusion provided on an edge of the outerperipheral surface to surround a sidewall of the package.
 2. The mold asclaimed in claim 1, wherein the injection and discharge holes extendfrom the upper surface to the outer peripheral surface of the lowersurface.
 3. The mold as claimed in claim 2, wherein the injection anddischarge holes are positioned to be opposite to each other with theconcave surface being interposed therebetween.
 4. The mold as claimed inclaim 1, wherein the outer peripheral surface is substantially flat. 5.The mold as claimed in claim 1, wherein the outer peripheral surface ofthe lower surface surrounds the injection and discharge holes.
 6. Amethod of forming a molding member, comprising: preparing a moldincluding an upper surface, a lower surface having an outer peripheralsurface and a concave surface surrounded by the outer peripheralsurface, injection and discharge holes extending from the upper surfaceto the lower surface, and a protrusion provided on an edge of the outerperipheral surface; preparing a package having an LED (Light EmittingDiode) mounted thereon; coupling the package and the mold so that theconcave surface covers the LED, the outer peripheral surface is adjacentto an upper surface of the package, an edge portion of the packageadjacent to the discharge hole is directed upward, and an other edgeportion opposite to the edge portion of the package body is directeddownward; and injecting a molding material into the injection hole,wherein the protrusion provided on an edge of the outer peripheralsurface surrounds the sidewall of the package.
 7. The method as claimedin claim 6, wherein the injection and discharge holes extend from theupper surface to the outer peripheral surface of the mold.
 8. The methodas claimed in claim 7, wherein the injection and discharge holes arepositioned to be opposite to each other with the concave surface beinginterposed therebetween.
 9. The method as claimed in claim 6, whereinthe injection hole is formed to be substantially perpendicular to anupper surface of the package or inclined upward from the lower surfaceto the upper surface of the mold, when the mold and the package arecoupled.
 10. The method as claimed in claim 7, wherein the outerperipheral surface is substantially flat.
 11. The method as claimed inclaim 6, wherein the preparation of the package having the LED mountedthereon comprises: preparing a lead frame having lead electrodes;forming on the lead frame a package body with a recess exposing the leadelectrodes, wherein the lead electrodes protrude out of the packagebody; mounting the LED in the recess region; and electrically connectingthe LED with the lead electrodes.
 12. The method as claimed in claim 11,wherein the package body is formed to have a guide groove for guidingthe molding material injected through the injection hole to the recessand a guide groove for guiding inner gas to the discharge hole.
 13. Themethod as claimed in claim 11, further comprising: coupling a heat sinkto the package body after the formation of the package body, wherein anupper surface of the heat sink protrudes into the recess region, and theLED is mounted on the upper surface of the heat sink.
 14. The method asclaimed in claim 11, further comprising: coupling a heat sink to thelead frame prior to the formation of the package body, wherein the LEDis mounted on an upper surface of the heat sink.
 15. The method asclaimed in claim 11, wherein coupling the package and the moldcomprises: inserting a lower part of the package body into a recess of alower jig, wherein the lead frame is seated on an upper surface of thelower jig; covering the lower jig and the lead frame using a cover seat,the cover seat having a through-hole through which the package body isallowed to pass for an upper part of the package body to protrude upwardfrom the cover seat; arranging the mold on the package body; pressingthe mold against the package body using an upper jig having athrough-hole for exposing the injection and discharge holes of the moldtherethrough; and fixing the mold by coupling the upper jig and thelower jig.
 16. The method as claimed in claim 15, wherein coupling thepackage and the mold further comprises rotating the jigs after the upperand lower jigs are coupled.
 17. The mold as claimed in claim 15, whereinthe outer peripheral surface of the lower surface surrounds theinjection and discharge holes.